Investors can get a bang for their buck from U.S. banks but don't expect it immediately, CNBC's Jim Cramer said Thursday.

"They're bargains but you can't expect them to react positively tomorrow. Too early," Cramer said on "Squawk Box."

Big banks JPMorgan Chase, Citigroup and Wells Fargo kicked off earnings season earlier in the day. Citi and JPMorgan beat expectations on the top and bottom line, while Wells Fargo's report came in mixed.

In early trading Thursday, shares of Wells Fargo were down more than 2 percent, while JPMorgan was up 1 percent and Citi was modestly higher.

The SPDR S&P Bank ETF (KBE) is down 7 percent over the past month, according to FactSet, as Wall Street's evaluates President Donald Trump's ability to impose simpler regulations. Bank stocks had initially rallied after the U.S. election.

On Wednesday, closely followed financials analyst Dick Bove of Rafferty Capital Markets told CNBC investors should get out of "treacherous" banks stocks, calling the reasons people are investing "simply wacko."